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4. Example of stunting: Egypt project

4.1. Infant length and its determinants

The mean birth length of infants was normal, with a Z score of 0.07 ±0.54 (SD). As in the Mexican and Kenyan children, the onset of deceleration of linear growth in the Egyptian children also started at 3 to 4 months of age (Table 11) (Rahmanifar et al., 1993). By 6 months of age the mean Z score was -1.01 ±0.03 (SD). There was no significant deficit in weight-for-length (WL). The main determinant of faltering in length was the percent of time ill with diarrheal episodes (R² = 0.09, P < 0.09, n = 34). Egyptian infants are fed sugar water daily, a likely source of pathogens.

4.2. Toddlers' length and its determinants

The Egyptian toddlers, at entry into the study at 18 months of age, were stunted with a mean Z score for LA of -1.94, and a normal WL (Table 11).

With only household and parental size variables available, multiple regression analysis was used to examine the length of the 18 month old child upon entry into the study. The best regression model for predicting toddler's size at 18 months included household sanitation, which accounted for 45% of the variation in height of boys. For girls only maternal height entered the equation. By comparison, the length of Kenyan toddlers at 18 months was predicted mainly by socioeconomic status and maternal and paternal height.

Table 11. Z scores for length-for-age and weight-for-age in 0 to 6-month-old Egyptian infants*, toddlers, and schoolchildren

* Semi-longitudinal data-sexes combined.
** na = Not available.

Linear growth velocity from 18 to 30 months remained at 70% of expected growth velocity. No relationships between initial weight and weight velocity, or initial length and length velocity were found. The most stunted children did not necessarily remain so, nor did they necessarily show catch-up growth.

The best predictor of rate of gain in linear growth over the 18 to 30 month period, was whether the child was still being breast fed after the age of 18 months. This variable accounted for 8% of the variation in length gain after controlling for sex, length at 18 months and for maternal height. None of the expected factors contributed additional predictive power (e.g. food intake, socioeconomic status, morbidity rate). About 60% of Egyptian toddlers had been completely weaned by 18 months, most between 15 to 18 months of age. The 40% still partially breast fed at 18 months were completely weaned between 18 to 28 months.

Partially breast fed toddlers received a mean of about 78% as much energy from foods other than breast milk as fully weaned toddlers. Thus, continued breast feeding at this age contributed, inferentially, less than a quarter of total calories. However, the effect appears to be not only due to the enhanced dietary quality and bioavailability provided by the relatively small amount of breast milk, but also to the fact that the quality of the non-breast-milk food was very different before and after complete weaning (Table 12). Toddler diets were essentially indistinguishable from those of schoolchildren and adults in terms of the percent of dietary energy from the various food groups. However, before complete weaning, toddlers received significantly less traditional bread and vegetables and more nutrient rich dairy products and chicken. Differences in micronutrient intake for weaned and non-weaned toddlers are shown in Table 13.

Weaning is a very significant developmental milestone in the Egyptian culture, and implies an important shift in all aspects of child care. The fully weaned child is essentially on its own with regard to participation in the household diet, while the still breast fed child is more actively fed and cared for by the mother. However, children weaned later do not get any less diarrhea than children weaned earlier.

Table 12. Comparison of Egyptian toddler diets before and after complete weaning (mean % of dietary energy)

4.3. School-age children's height arid its determinants

Moderate stunting was seen in the schoolchildren with a mean Z score for HA of -1.03 ±0.93 (SD). Less stunting was seen than in toddlers, with some catch-up having occurred. However, over 51% of schoolchildren had HA Z scores of -1, and 16.4% had HA Z scores below -2.

Parental height, but not weight or BMI, predicted both initial HA and WA for the 7-year-old children upon entry into the study. For girls, sanitation variables were powerful predictors of body size. A multiple regression model including father's height, a kitchen contained within the household and piped water explained 50% of the variation in height for girls. For boys maternal and paternal height and sanitation predicted 30% of the variability in height.

For height gain in boys from age 7 to 9 years, maternal literacy accounted for 9% of the variability. For the girls, maternal literacy and percent energy from meat (both positive), and phytate:zinc molar ratio and household crowding (both negative) accounted for 23% of the variation in linear growth. Thus diet quality was relatively more important for girls, who may have been more deprived than the boys. Maternal education was an important factor in height gain both in boys and girls. As for birth order, being the oldest child had a negative impact on height for girls but not for boys.

Table 13. Dietary quality for toddlers before and after complete weaning; percent of mineral and vitamin intake from food groups (mean)

5. Summary

The etiology of the early onset of stunting is diverse among populations of varying biological, environmental and cultural circumstances. This is exemplified within the Nutrition CRSP project, which took place in three different populations and ecological conditions. Within each study area a different mix and varying proportions of causative factors were identified. At least in Kenya, and probably in Mexico, the problem has its antecedents in prepregnancy and pregnancy. Powerful determinants of the infants' size at birth and during the first 6 months of life are maternal size upon entry into pregnancy, and weight and fat gain during pregnancy and lactation. In all three countries a low pregnancy weight gain was observed. Notably in Kenya, where the energy intake of the mother decreases progressively throughout pregnancy, not only do mothers gain only half as much as European or North American women, but they even lose weight and fat in the last month of pregnancy, and some mothers gain no weight or lose weight during the whole of pregnancy.

Mothers in Kenya start lactation with relatively poor fat stores. Although their energy intake increases somewhat during lactation, preliminary estimates suggest that these increases may be insufficient to maintain their bodily integrity, to carry out their normal tasks of daily living, and to produce a sufficient amount of milk for optimal infant growth.

In addition to an energy deficit, diet quality is a problem, particularly in Kenya and Mexico and less so in Egypt. Intakes of animal products and animal protein are very low. Zinc and iron intakes are not only low, but the bioavailability of these nutrients is poor because of the high phytate, fiber and tea content of the diet. Also vitamin B₁₂ intake is extremely low, and at least mild-to-moderate iodine deficiency (IDD) is present in Kenya. The above micronutrients have been demonstrated to affect the linear growth of the Kenyan children, even after confounding factors have been controlled.

The early use of supplemental feeding in Kenya is a double-edged sword. On the one hand, there is a slight increase in febrile illness and possible displacement of breast milk intake in the supplemented infants, although mothers do not decrease breast feeding frequency and duration. On the other hand, even the modest amounts of available zinc and B₁₂ in supplemental foods appear to have a positive effect on linear growth.

Morbidity, particularly in the Egyptian children, but also in the Kenyan infants and toddlers, has a negative impact on attained length in the 6 month old infant and also on the rate of linear growth. Diarrheal disease is very frequent in Egyptian infants and toddlers. Household sanitation level in Egypt is a potent determinant of growth, no doubt mediated through diarrheal disease.

In addition to parental size and household sanitation, cultural patterns of child rearing appear important, as demonstrated in the Egypt study. An important determinant of the toddler's linear growth from 18 to 30 months was whether or not it was still being breast fed. Those who were partially breast fed grew better than those who were fully weaned. Not only did the partially breast fed child benefit from the nutritional advantages of breast milk, but also from the higher quality supplemental feedings compared to the fully weaned child who partook of the regular household diet. Apparently, the breast fed child is perceived as requiting more nurturing.

In all three country studies the major deceleration of growth occurs in the first 6 months of life and probably continues throughout the first 12 to 18 months (although not observed). From 18 months onward the quantity and quality of the diet and environmental factors do not permit catch-up to the normal or near normal centiles observed in the newborns. Beyond infancy the rate of growth is normal but at a very low level, below the 5th centile in Kenya and Mexico. Little catch-up is seen in the schoolchildren and in late adolescence in Kenya, although the Egyptian children appear to improve in linear growth, as evidenced by improved height-forage Z scores compared with the toddlers.

Acknowledgements - Research was supported by: USAID Office of Nutrition Grant, No. DAN-1309-SS-1070-00 and Cooperative Agreement DAN 1309-A-00-9090-00 World Bank (Data Analysis)

Special acknowledgements are made to the Kenya project field and support staff at UCLA School of Public Health and University of California, Berkeley (UCB). Department of Nutrition and the University of Nairobi, Kenya: N.O. Bwibo, MD, PhD: Cp PI (University of Nairobi). A.A.J. Jansen, MD, PhD: Kenya Project: Training and supervision of anthropometry and pregnancy outcome. M. Baksh, PhD: Kenya project: Former field director. E. Carter, MD, PhD: Kenya project: Former field director. S. Oace, PhD: Analyses of vitamin B₁₂ levels in breast milk (UCB). S. Murphy, RD, PhD: Nutrient data base (UCB). D. Calloway, PhD: Program Director Nutrition CRSP and nutrient data base development (UCB). G. Beaton, PhD: Consultant to Nutrition CRSP Management Entity (UCB). S.W. Andersson, MS: Directed food intake data collection in the field. L. Ferguson, PhD: Data analyses and statistical advice.

Special acknowledgements are made to the Egypt project field and support staff at UCLA School of Public Health, University of Kansas, and Purdue University, and the Nutrition Institute, Cairo, Egypt: O. Galal, MD, PhD: Co-PI (UCLA). N. Jerome, PhD: Co-PI (University of Kansas). N. Kirksey, PhD: Co-PI (Purdue University). M. Shaheen, MBBCH, MSc: Data entry (UCLA). F. Shaheen, MD, PhD: Formal field director (Institute of Nutrition). W. Moussa MD, PhD: Food intake (Nutrition Institute).

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